Matter Wave Theory Question?

Question

For the last few years Ive tried my best to understand why I cant pinpoint a particles position and momentum at the same time. Im not a student, just someone who likes to learn.

Today I came upon a Pittsburgh University site that, I believe, put it together for me.

Here goes: a sine wave is uniform and has a definite momentum. The wave represents a particle spread throughout space.

When we add multiple waves together, the result is one wave that is no longer uniform, it tends to be concentraded in one spot. That concentration represents the particles position. But since we dont have a uniform wave, we no longer know the momentum.

Do I understand this correctly? Could you add anything else?

Andrew Smith · Answer

There are many ways to view this.  Yours is only one.

Consider this.
To know where something is you must measure it.
To measure it you must "see" it.
To do this you have to hit it with something, for example a photon.
But this photon causes a change to the item being viewed.
Using a high energy photon causes a greater change to the momentum of the particle being viewed.
But using a low energy photon causes IT to have a longer wavelength and it scatters from the particle being viewed making it impossible to determine the exact position of the object.

So you can increase the accuracy of the measurement of position by making the momentum less certain and vice versa.

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Matter Wave Theory Question?

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